The present invention relates to a heat-resistant silicone fluid composition or, more particularly, to a heat-resistant silicone fluid composition having excellent durability even by prolonged heating at an elevated temperature of 200.degree. C. or higher.
Although silicone fluids are superior in the heat resistance or stability at high temperatures to mineral oils and oils of animal or vegetable origin, as is well known, silicone fluids are also not free from gradual oxidation in air when heated at 200.degree. C. or higher so that no satisfactory durability can be expected for silicone fluids used as a lubricating oil or a working fluid exposed to relatively high temperatures. Accordingly, it is a common practice that a silicone fluid to be used at an elevated temperature is admixed with an antioxidant in order to enhance the durability or usuable life while a problem in the use of an antioxidant in silicone fluids is that most of the antioxidant compounds are insoluble in or incompatible with silicone fluids so that no uniform silicone fluid composition can be obtained by the admixture of an antioxidant or the antioxidant dissolved or dispersed by a mechanical means in a silicone fluid with heating may be readily lost by dissipation when the silicone fluid is exposed to a high temperature atmosphere so that no satisfactory results can be obtained in this way of admixing a conventional antioxidant.